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issued, which lies there now, rugged and black, covering the plain with volcanic cinders to the depth of about twenty feet.

Similar extinct volcanoes are found in the south of Sicily, the neighbourhood of Naples, Hungary, the lower provinces of the Rhine, and the north of Spain.

In England, Scotland, and Ireland, although no such specimens of extinct volcanoes, in the form of hills with cones and craters, are found, yet rocks of volcanic origin abound; and there can be no doubt but that the remarkable basaltic rocks of Staffa and the Giant's Causeway are the productions of an extinct volcano.

The absence of cones and craters, and of streams of cooled lava issuing from the bases of the basaltic hills of the British Isles, is owing simply to the circumstance that the eruptions of these volcanoes, in the period of their activity, took place under the bed of the ocean.